InvSR endpoint auto-falls back to MewZoom 4X on CPU

app.py

@@ -191,5 +191,18 @@ async def route_metrics(file: UploadFile = File(...)):
 
 
 @app.post("/upscale/invsr")
-async def route_invsr(file: UploadFile = File(...)):
-    raise HTTPException(400, detail="InvSR (diffusion 4X) needs GPU. This Space is CPU. Use /upscale/2x or /upscale/4x.")
+async def route_invsr(
+    file: UploadFile = File(...),
+    num_steps: int = Query(1, ge=1, le=5),
+    tile_size: int = Query(128, ge=64, le=512),
+):
+    if torch.cuda.is_available():
+        raise HTTPException(501, detail="InvSR GPU pipeline not bundled in this Space. Use the Colab notebook.")
+    # Fallback to MewZoom 4X on CPU
+    logger.info("InvSR endpoint called on CPU — falling back to MewZoom 4X")
+    result, info = upscale_image(await file.read(), "4x")
+    info["fallback"] = "InvSR not available on CPU, used MewZoom 4X instead"
+    return StreamingResponse(
+        BytesIO(result), media_type="image/png",
+        headers={"X-Info": json.dumps(info)},
+    )